The industrial byproduct fly ash produced by thermal power plant is increasing every year and the amount is about 10 billion tons produced per annum in China. On the one hand, fly ash is a pollutant causing several environmental problems. On the other hand, it is useful resource to prepare alumina. Therefore, it is important to realize high value comprehensive utilization of fly ash.

 Although scientists have studied for over forty years to get alumina from low grade aluminum resource by leaching method, the increasing cost for equipment corrosion caused by high concentration hydrochloric acid and extraction of iron is key problem to solve.

 Professor LI Zhibao from Institute of Process Engineering, Chinese Academy of Sciences and Professor Asselin from the University of British Columbia, Canada developed a novel process to prepare alumina. AlCl₃·6H₂O was recovered from fly ash by salting-out crystallization with FeCl₂.

 The technology mainly included four steps leaching, reduction, salting-out crystallization and filtering and washing. Firstly, the fly ash was leached by hydrochloric acid. Secondly, the iron fillings were added into the leached filtrate to reduce the Fe³⁺. Thirdly, the leaching solution was evaporated and crystallized to AlCl₃·6H₂O. Fourthly, the AlCl₃·6H₂O crystal was roasted to get alumina.

 The process provided an efficient method to separate AlCl₃·6H₂O from fly ash and had great potential in economic field. The results were published on Industrial & Engineering Chemisry Research.